SeaMonkey 2.49.2 is out
The developer's of the Internet application suite SeaMonkey have released version 2.49.2 of the application for all supported operating systems. They note that the release won't be offered via the integrated updating feature for most configurations because of changes that it introduces.
Users who want to upgrade to the new version may need to download it from the project website to install it manually because of that.
It is highly recommended that you back up the profile folder before you run the update as some files may not be compatible anymore with older versions after the upgrade. In other words: you may not go back to a previous version without losing access to some data.
Mozilla changed the internal format of the browsing history database. While that is a non-issue if you update from a version of SeaMonkey that uses the old format to a version that uses the new, it becomes an issue if you want to downgrade again as this is not possible.
SeaMonkey will rename your history file to places.sqlite.corrupt and create a new places.sqlite file, effectively resetting your browsing history.
SeaMonkey users who use the built-in email client may run into issues as well. Summary files may not be read properly if you downgrade SeaMonkey after having upgraded it to the latest version. SeaMonkey users should delete the .msffiles in the local folders and for Pop3 accounts to avoid data loss and resolve the issue.
The release notes offer further information on known issues and incompatibilities. The team notes that some extensions may not work properly anymore in SeaMonkey 2.49.2. The browser is based on Firefox 52.6 ESR currently.
SeaMonkey does not support WebExtensions currently because of that. This is going to change but likely not anymore in 2018.
I suggest you read the full release notes on the official website for a full rundown on changes and how these may affect you.
Now You: Do you or have you used SeaMonkey?